The New York Police Department is investigating testimony during an officer's manslaughter trial that some police weren't properly trained in CPR.

Peter Liang was convicted Feb. 11 in the death of Akai Gurley. Liang accidentally fired into a darkened stairwell in a public housing project, killing the 28-year-old Gurley.

Liang and his partner, Sean Landau, both testified they received little CPR training. Liang said he didn't try to revive Gurley because he felt he wasn't as qualified as Gurley's girlfriend. The girlfriend was being coached by a 911 operator.

William Bratton said Tuesday that internal affairs would interview the entire class that graduated with the pair in 2013. He said he will ensure proper training is received.

Landau was not charged criminally. Both he and Liang were fired.